This invention pertains to the attenuating of the noise of fluid (preferably gas) in non-axisymmetric turbulent flow and, more particularly, to a device for attentuating the noise of gas in a conduit comprising a plurality of nested tubes eccentrically arranged to each other and disposed in substantially parallel relationship to each other along the axis of the conduit. Preferably, the nested tubes are foraminous or perforated along their lengths.
Devices are known which break up a fluid stream into a plurality of parallel flow paths for reducing noise resulting from the flowing fluid. Nagel U.S. Pat. No. 3,630,229 shows a quiet flow fluid regulator comprising a ball valve, a sealing face insert downstream of the ball valve having a plurality of bores therein, and a plurality of parallel flow tubes communicating with the bores in said sealing face insert. The parallel flow tubes comprise a frictional pressure drop means.Vibration absorbing material is packed around the flow tubes to absorb vibrational or acoustic engergy.
Milroy U.S. Pat. No. 3,170,483 reveals a quiet flow regulator valve having a flow silencing tube bundle downstream of a gate valve.
Bauman U.S. Pat. No. 4,085,774 discloses anticavitation and low noise means for a rotary valve having a plug with at least a partially spherical surface. The low noise means comprises a plate having a concave spherical indentation closely engaging the spherical surface of the plug and provided with a plurality of individual flow passages.
Kolb U.S. Pat. No. 4,180,100 pertains to a low noise generation controlvalve having a pluraity of small resisting bodies filling the passage in the valve about the cage. A valve plug movable in the cage controls the flow of fluid through the passage. The patent suggests that the small resisting bodies could be made of metallic wool.
Also, it is known to provide fluid resistant devices in ducts to reduce high static-pressure of a liquid or gas without the undesirable by-products of a high aerondynamic noise level in the case of a compressible fluid, such as gas, or cavitation and erosion in case of a liquid. Such fluid resistant devices may comprise spaced apart perforated plates, as in Baumann U.S. Pat. No. 3,665,965, or stacked plates arranged in a selected overlap pattern to provide desired tortuous or serpentine flow paths through the stacked plates, as in Baumann U.S. Pat. No. 4,050,479, or a stack of washer-like members, as in Vick U.S. Pat. No. 4,000,878 or Kluczunski U.S. Pat. No. 4,008,737.
Hasinger U.S. Pat. No. 4,058,141 suggests a supersonic flow diffuser having a plurality of blades therein for dividing the diffuser channel into a plurality of approximately axisymmetric ducts.
Some of these devices for attenuating the noise of gases are complex, cumbersome and costly. Others do not effectively convert non-axisymmetric flow from a valve to desirable axisymmetric flow.
An object of the present invention is to provide a novel device for attenuating noise of fluid in non-axisymmetric turbulent flow that overcomes the disadvantages and deficiencies of prior devices.
Another object of this invention is to provide an improved device for attentuating the noise of gas in non-axisymmetric turbulent flow in a conduit comprising a plurality of nested tubes, which are eccentrically arranged with respect to each other and are disposed in parallel relationship to one another along the longitudinal axis of the conduit.
Yet another object of the present invention is to provide an improved noise attenuating device for gas in non-axisymmetric turbulent flow in a conduit, such device comprising in one form a plurality of foraminous nested tubes arranged in parallel relationship along the longitudinal axis of the conduit, said tubes being eccentrically aligned with respect to each other such that a surface of each tube is substantially in line contact with a surface of each adjacent tube along their longitudinal lengths, the line contact between all of said tubes being at substantially a common line allowing for the thickness of the walls of the tubes.
A further object of the present invention is to provide an improved gas attenuating device for gas in turbulent flow in a conduit, such device comprising in a second form a plurality of foraminous nested tubes arranged in substantially parallel relationship along the longitudinal axis of the conduit, said tubes being eccentrically aligned with respect to each other, and a bracket extending between and connected to each of said tubes to retain the tubes in desired relationship in the conduit.
Still another object of the present invention is to provide an improved device for attenuating the noise of gas in turbulent flow closely downstream of a non-axisymmetric discharging valve and for converting the non-axisymmetric flow to substantially axisymmetric flow, i.e., fully developed pipe flow.
Other objects and advantages of the present invention will be made more apparent in the description which follows.